In the past, sodium hypochlorite was used as a bactericide in the sterilization of pipelines and containers in a food plant. In recent years, the trend is using peracetic acid as a bactericide. Conventionally, wastewater generated from sterilization using sodium hypochlorite and the rinse water thereafter were mixed and treated together with wastewater from other process, due to a high concentration of ions contained in the wastewater from sterilization.
Peracetic acid is produced according to the following formula:CH3COOH+H2O2→CH3COOOH+H2OTherefore, main ingredients of a peracetic acid bactericide include acetic acid (35%), peracetic acid (15%), hydrogen peroxide (25%), and the balance water (25%), wherein peracetic acid is the main bactericide. When a peracetic acid bactericide is used in washing pipelines and containers in a food plant, soft water is used to prepare the bactericide with a desired concentration. The wastewater generated thereafter generally is deemed as unable of being effectively treated individually due to a high concentration of bactericide contained in the wastewater. Therefore, such wastewater is mixed with wastewater from other processes and then transported to a general treatment plant.